Military combat has always been a dangerous undertaking, to say the least. But the threat troops face today is unlike any they have encountered before. The enemy often consists of non-uniformed personnel operating individually or in small groups. And they strike populated urban areas with little or no regard for civilian causalities.
When an urban area is under attack, a common response strategy is to emplace ground forces on the city's outskirt. From this perimeter, buildings (and/or other vertical obstructions) obscure targets. They also create “dead spaces” unreachable by weapons with traditional ballistic trajectories. The enemy can be assumed to take full advantage of the hiding places and blind spots afforded by urban structures. And they can also be expected to niche target operations so that anything but a high-precision hit will result in collateral damage.
For these reasons, accurate and realtime surveillance data can be more critical in an urban combat area than in most other battlefields. At the same time, effective observation in such a setting is dangerous and difficult. An on-foot forward observer is often out of the question, as he quickly becomes a sitting duck for rooftop snipers. Even if a forward observer is lucky enough to slip past unfriendly fire, he may not be able to reach an effective vantage to gather meaningful intelligence.
Aerial surveillance erases most view-point problems and, if an unmanned vehicle is used to collect the survey data, human life is spared. But surveillance aircraft tend to be loud and thus audibly announce their approach to the enemy. And perhaps more importantly, an aerial vehicle (manned or unmanned) may not be available in a timely manner to support ground forces. Aerial surveillance vehicles do not come cheap, and keeping an inventory of even one vehicle near each major city has been considered cost prohibitive. Urban combat commonly occurs suddenly without warning, and waiting for aerial surveillance support to arrive is often not a viable option.